A thermal testing device to determine thermal conductivity and specific heat capacity of saturated and dry soils

This study focuses on the determination of two thermal properties of soil that are critical in understanding its heating and cooling behaviour in a variety of geotechnical and geoenvironmental engineering problems. Those properties are the thermal conductivity and specific heat capacity. The study presents a new testing device, and a theory-based interpretation procedure, so the properties can be determined for saturated or dry soils using just one sample and one set of test results. The testing device enables experiments to be conducted on a cylindrical soil sample that is subjected to constant thermal loads at its outer boundaries. Temperature changes at different locations and times inside the soil sample are recorded. Interpretations of the measured temperature changes adopt an analytical solution for one-dimensional transient heat transfer in which thermal conductivity and specific heat capacity are assumed to remain constant. This is found to be the case, approximately, in the experiments. It also requires the heat exchange efficiency factor of the testing device to be constant and independent of test soil type. This was confirmed to be true. The new testing device and interpretation procedure offer reliable measurements and may be used in industry or research.